As of 11:50 CDT

Weather in Harper, IL

73°

Harper, Wednesday, 7 October, 11:50

Clear. Feels like 72°. High 74°, low 55°.

Pressure29.85 inHg

Wind6.9 mph NW

Humidity32%

Visibility6.2 mi

Dew point41°

See detailed hourly forecast

Monthly outlook for Harper, IL: average high 64°, average low 47.1°. That is 1.8° above the climate normal for October. Precipitation is expected on 2 days (about 0.4 inches), against a normal of 5 days and 1.5 inches. The warmest day looks like 10 October (78.6°), the coolest 14 October (37°).

64°/47.1°

Average high / low

+1.8°

Above normal

2 / 5

Wet days / normal

0.4 in

Precipitation this month

Ten-day blocks vs climate normal

Period	Forecast high	Normal	Difference
7 October – 16 October	69.9°	62°	+4.3°
17 October – 26 October	54.4°	57.7°	-1.8°
27 October – 5 November	at normal	53.4°	—

October records over 66 years

86.4°3 October 2025All-time high

21.4°30 October 1988All-time low

Climate normals and records are computed from the nearest reference point — Freeport (10 mi).

Thu, 0870° / 48°

70 °

Harper, Thursday, 8 October

Mostly clear. High 70°, low 48°.

Pressure30.12 inHg

Wind6 mph NW

Humidity49%

Visibility6.2 mi

Dew point44°

Fri, 0971° / 48°

0.13

71 °

Harper, Friday, 9 October

Rain. High 71°, low 48°.

Pressure30.12 inHg

Wind11 mph SE

Humidity73%

Visibility6.2 mi

Dew point55°

Sat, 1079° / 61°

79 °

Harper, Saturday, 10 October

Clear. High 79°, low 61°.

Pressure30.06 inHg

Wind13.4 mph S

Humidity53%

Visibility6.2 mi

Dew point56°

Sun, 1172° / 59°

72 °

Harper, Sunday, 11 October

Overcast. High 72°, low 59°.

Pressure29.88 inHg

Wind9.4 mph S

Humidity60%

Visibility—

Dew point54°

Mon, 1275° / 56°

0.21

75 °

Harper, Monday, 12 October

Rain. High 75°, low 56°.

Pressure29.80 inHg

Wind13 mph N

Humidity65%

Visibility—

Dew point59°

Tue, 1359° / 42°

0.01

59 °

Harper, Tuesday, 13 October

Light rain. High 59°, low 42°.

Pressure30.03 inHg

Wind18.3 mph NW

Humidity71%

Visibility—

Dew point43°

Wed, 1459° / 37°

59 °

Harper, Wednesday, 14 October

Overcast. High 59°, low 37°.

Pressure30.21 inHg

Wind10.8 mph SE

Humidity55%

Visibility—

Dew point38°

Thu, 1573° / 50°

73 °

Harper, Thursday, 15 October

Overcast. High 73°, low 50°.

Pressure29.85 inHg

Wind18.7 mph S

Humidity49%

Visibility—

Dew point46°

Fri, 1668° / 49°

68 °

Harper, Friday, 16 October

Light rain. High 68°, low 49°.

Pressure29.83 inHg

Wind15.9 mph W

Humidity61%

Visibility—

Dew point50°

Sat, 1751° / 48°

51 °

Harper, Saturday, 17 October

Overcast. High 51°, low 48°.

Pressure30.00 inHg

Wind14.5 mph W

Humidity72%

Visibility—

Dew point42°

Sun, 1847° / 43°

47 °

Harper, Sunday, 18 October

Light rain. High 47°, low 43°.

Pressure30.06 inHg

Wind14 mph W

Humidity78%

Visibility—

Dew point37°

Mon, 1956° / 39°

56 °

Harper, Monday, 19 October

Partly cloudy. High 56°, low 39°.

Pressure30.18 inHg

Wind10.2 mph W

Humidity62%

Visibility—

Dew point39°

Tue, 2062° / 42°

62 °

Harper, Tuesday, 20 October

Clear. High 62°, low 42°.

Pressure30.18 inHg

Wind7.5 mph NW

Humidity55%

Visibility—

Dew point42°

Wed, 2155° / 38°

55 °

Harper, Wednesday, 21 October

Clear. High 55°, low 38°.

Pressure30.30 inHg

Wind8.5 mph E

Humidity51%

Visibility—

Dew point33°

Thu, 2256° / 39°

56 °

Harper, Thursday, 22 October

Overcast. High 56°, low 39°.

Pressure30.30 inHg

Wind6.5 mph E

Humidity54%

Visibility—

Dew point35°

From day 17 onward the outlook is built from 60-year climate statistics

Fri, 2358° / 43°

0.13

58 °

Harper, Friday, 23 October

Climate normal for this date — 60-year average.

Average high58°

Average low43°

Average precipitation0.13 in

Chance of precipitation43%

Record high79° (1963)

Record low24° (1969)

Sat, 2456° / 43°

0.11

56 °

Harper, Saturday, 24 October

Climate normal for this date — 60-year average.

Average high56°

Average low43°

Average precipitation0.11 in

Chance of precipitation35%

Record high78° (1963)

Record low23° (1981)

Sun, 2556° / 41°

0.08

56 °

Harper, Sunday, 25 October

Climate normal for this date — 60-year average.

Average high56°

Average low41°

Average precipitation0.08 in

Chance of precipitation23%

Record high76° (1989)

Record low27° (2006)

Mon, 2655° / 41°

0.1

55 °

Harper, Monday, 26 October

Climate normal for this date — 60-year average.

Average high55°

Average low41°

Average precipitation0.1 in

Chance of precipitation25%

Record high77° (1963)

Record low23° (1962)

Tue, 2755° / 40°

0.07

55 °

Harper, Tuesday, 27 October

Climate normal for this date — 60-year average.

Average high55°

Average low40°

Average precipitation0.07 in

Chance of precipitation25%

Record high74° (2014)

Record low25° (1997)

Wed, 2855° / 40°

0.06

55 °

Harper, Wednesday, 28 October

Climate normal for this date — 60-year average.

Average high55°

Average low40°

Average precipitation0.06 in

Chance of precipitation22%

Record high71° (1999)

Record low24° (1969)

Thu, 2955° / 40°

0.06

55 °

Harper, Thursday, 29 October

Climate normal for this date — 60-year average.

Average high55°

Average low40°

Average precipitation0.06 in

Chance of precipitation23%

Record high78° (2024)

Record low23° (1980)

Fri, 3056° / 41°

0.1

56 °

Harper, Friday, 30 October

Climate normal for this date — 60-year average.

Average high56°

Average low41°

Average precipitation0.1 in

Chance of precipitation32%

Record high77° (2024)

Record low21° (1988)

Sat, 3154° / 41°

0.11

54 °

Harper, Saturday, 31 October

Climate normal for this date — 60-year average.

Average high54°

Average low41°

Average precipitation0.11 in

Chance of precipitation37%

Record high71° (1974)

Record low24° (2019)

Sun, 0153° / 40°

0.2

53 °

Harper, Sunday, 1 November

Climate normal for this date — 60-year average.

Average high53°

Average low40°

Average precipitation0.2 in

Chance of precipitation38%

Record high74° (2000)

Record low20° (2019)

Mon, 0252° / 39°

0.13

52 °

Harper, Monday, 2 November

Climate normal for this date — 60-year average.

Average high52°

Average low39°

Average precipitation0.13 in

Chance of precipitation32%

Record high73° (1961)

Record low20° (1991)

Tue, 0352° / 38°

0.06

52 °

Harper, Tuesday, 3 November

Climate normal for this date — 60-year average.

Average high52°

Average low38°

Average precipitation0.06 in

Chance of precipitation27%

Record high71° (1964)

Record low15° (1991)

Wed, 0451° / 39°

0.09

51 °

Harper, Wednesday, 4 November

Climate normal for this date — 60-year average.

Average high51°

Average low39°

Average precipitation0.09 in

Chance of precipitation28%

Record high70° (2015)

Record low13° (1991)

Thu, 0551° / 37°

0.1

51 °

Harper, Thursday, 5 November

Climate normal for this date — 60-year average.

Average high51°

Average low37°

Average precipitation0.1 in

Chance of precipitation22%

Record high70° (1978)

Record low18° (1991)

About the monthly outlook

How accurate is a 30-day forecast?

The first 16 days come from weather models — reliable for the first 3–5 days and progressively less so after that. Days 17 through 30 for Harper, IL are built from the climate normal, the 60-year average, so they show typical weather for those dates rather than a specific forecast.

What does "above normal" mean?

We compare the forecast against the climate normal for those exact calendar days, computed from 60 years of observations. The deviation shows how much the coming month differs from a typical one.

Where do the 66-year records come from?

They are real temperature extremes recorded in Harper, IL since 1960: the highest and lowest reading for each calendar date, with the year it happened.

How often is it updated?

The forecast portion refreshes every hour; the climate portion is based on long-term data and stays stable.